Working Principle:​ The electronic controller sends an electrical command signal to the torque motor servo valve inside the TM-55 actuator. The servo valve generates a pressure differential to drive the secondary spool, regulating hydraulic oil flow to both ends of the double-acting servo piston. Piston movement drives the final output shaft to rotate, thereby driving the meter sleeve of the rotary gas valve to change its opening. The built-in electrical position sensor continuously detects the actuator/valve position and feeds back to the controller, forming a high-precision closed-loop position control. On loss of control system power, the spring-loaded mechanism of the actuator pushes the valve toward the minimum fuel position, realizing fail-safe protection.